i'll be the first one :) and what's the difference between the sr80i and SR60i?

Too late! There have been many, many discussions about this topic.

These headphones used to sound different when they came with different ear pads. With the same pads, what ever sonic difference there might be is small. There is really no point losing too much sleep over which one to get.

Now that I think of it, you can put the SR-80 driver inside the HD-497 shell. Too bad it's discontinued. That's an open headphone and would require a recable obviously.
I actually found that the Maxell DHP-II memory foam pads fit it!

Generally closing an open back headphone (especially something that's as open as a Grado) will destroy the sound signature. Now the result itself may not be terrible, but it will be nothing like the original. Headphile has been doing this for years with Sennheisers and Grados, and usually the resale and second-hand market for the creations is abysmal relative to their initial cost. That should tell you something.

Now, having said that, I'm sure if you spent enough time tweaking you could get something fairly decent, but it would almost certainly be unique from the Grado experience. Putting them in another shell will accomplish that, and who knows what the outcome will be like. That's why SR-60s are a good place to start (or iGrados, iirc they use the same size drivers) if you're ripping them up - better to sink a $70 pair of headphones than a $700 pair.